Results 1 to 5 of 5
  1. #1

    Boring, pistons, carbs, etc.

    Well I have my engine strip-down in motion and so far from the looks of it the main bearings and rod bearings are in good shape, which hopefully means the crank index is ok (how can I check the index?). My original plan was to clean everything up and install a new piston and call it a day but speed is addictive and since I have a good amount of money in savings and I am making good money this summer I wanted to get some more power from my ski.

    As of right now, my plan is to get a extended pump, Boyseen Power reeds, 650 dry pipe, and 785 CDI. Since my cylinders need honing, I was leaning towards having them bored a little more; I think my cylinders have already been bored becasue the pistons have '0.25' stamped on them. So I'll probably take them to 0.50 or 0.75. I'll most likely have Sharp's take care of the machine work.

    For pistons; is there a better brand or are they basically the same (Weisco, WSM)? I heard forged pistons suck in these applications. Any truth to that?

    For carbs I was planning on running rejetted stock Mikunis. Good idea or bad idea?

    All feedback on this will be appreciated!

  2. #2
    Jug Inspector
    Join Date
    Aug 2006
    Chicago Burbs
    Wisecos are forged and require a larger clearance.. also take care and time when warming up so you don't cold-seize. It's not a big deal, just be aware of it.


  3. #3
    Connecticut CrazyA's Avatar
    Join Date
    Nov 2005
    I would say save some money and stick with the stock carbs.... THEY ARE PLENTY for this application.

    Also, if you want to talk to Richie, maybe he can hook you up on a sleeper package. We were just talking about this yesterday!!!! (the 750 specifically)

    He likes to SLIGHTLY port the intake area on the cases, clean up the transfers, SLIGHTLY square off the exhaust, and do a little magic on the heads.

    All with stock electrics, stock exhaust and stock carbs. Pump gas. Riding style determines if he'll suggest flame arrestors.

    He says they wake up quite a bit for what they are. Give him a call and see. It may be cheaper to have him do all that and assemble it than it would be to collect all the other parts, or close???


  4. #4
    Edit: Just got off the phone with Richie.

    He said the dry pipe and 785 box weren't really worth it. He said if anything, a 780 box would do more good on this engine. He also suggested having the cylinders ported and honed. Rejet the stock carbs to a 105 main jet and get an extended pump w/ 12/17 prop and sponsons to call it a day.

    Sounds like a plan.
    Last edited by SantaCruz163; 05-30-2007 at 05:50 PM.

  5. #5
    1FASTXC's Avatar
    Join Date
    Mar 2007
    If it were me, i would get your crank professionally checked out while you have it torn down this far. Crank guys with years of experience will find things that the average guy doesn't know were wrong. Could save you money and headaches in the end. I have a local guy just miles from my house, so i always do this, and at times when i thought bearings were ok, he said they were junk. They didn't "feel" bad to me, but he has alot more experience with them. If there's nothing wrong, the cost to just check it out will be minimal. Just my .02.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Fs: gp 800 cases/ carbs etc.
    By crashhard in forum Yamaha Classifieds
    Replies: 6
    Last Post: 09-04-2010, 09:46 PM
  2. FS 2 WSM std bore pistons for 951 carbed....
    By OutlawGPR in forum Sea Doo 2 Stroke Skis
    Replies: 2
    Last Post: 06-27-2010, 09:24 PM
  3. Big Bore Pistons Over 88mm
    By #.0 in forum Yamaha PWC Performance (2-stroke)
    Replies: 17
    Last Post: 04-10-2009, 06:14 AM
  4. F.S. 780 cyl, std bore with piston, rings etc
    By john zigler in forum Polaris Classifieds
    Replies: 0
    Last Post: 10-08-2008, 12:50 PM
  5. big bore pistons
    By billy's gpr in forum Yamaha PWC Performance (2-stroke)
    Replies: 0
    Last Post: 10-11-2007, 11:29 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts